Corrosion

Corrosion is pile worn lower in certain dyed colours than in those around it: most often dark browns and blacks fixed with iron, and in some older rugs greens made with copper salts. The metal weakens the wool, so over decades that pile wears down. Undyed natural brown or camel wool is not subject to this dye-related corrosion. Shearing before export reduces the visible trough.

Also oxidation · oxidised · oxidized · iron corrosion · corroded browns · etched pile

See also Mordant, Oak gall, Walnut husk, Undyed wool (khodrang)

Last reviewed November 2026